1. Field of the Invention
This disclosure generally relates to automatic data collection (ADC) and more particularly to radio-frequency identification.
2. Description of the Related Art
The ADC field is generally directed to the use of devices and methods for automatically capturing data typically encoded in data carriers such as machine-readable symbols or radio-frequency identification (RFID) tags carried by the item to which the data relates. An ADC device may be embedded in a carrier, such as a metal or plastic carrier, or in an item, such as an asset, to which the data relates. A variety of ADC devices and ADC media are ubiquitous and well known, and are often used for tracking inventory.
RFID tags typically include an RFID substrate carrying a circuitry such as a semiconductor device including memory and one or more conductive traces that form an antenna. Typically, RFID tags act as transponders, providing information stored in the semiconductor device in response to a radio-frequency (RF) signal, commonly referred to as an interrogation signal, received at the antenna from a reader or interrogator. Some RFID tags include security measures, such as passwords and/or encryption. Many RFID tags also permit information to be written or stored in the semiconductor memory via an RF signal. As used herein, radio-frequency communications include communications in any frequency band or range suitable for wireless communications, including those commonly referred to as the radio wavelength and the microwave wavelength portions of the electromagnetic spectrum.
RFID tags that include a discrete power source, for example a battery, are commonly referred to as active devices. RFID devices that rely on an RF signal to derive power are commonly referred to as passive devices. RFID tags may employ both active and passive power sources.
An RFID tag may fail, which can lead to substantial costs particularly when the RFID tag is used to control inventory or when the RFID tag is embedded in an expensive carrier or in the item to which the data relates.